Control óptico de la fuerza del campo electromagnético inducido por campos electromagnéticos tridimensionales

The selective enhancement or suppression of optically induced electric and magnetic forces in dielectric nanoparticles through dynamic field tuning remains a significant challenge. Herein, we demonstrate a phase-based approach that enables continuous and quantitative modulation of the balance between electric and magnetic optical forces on germanium (Ge) nanospheres through phase-dependent three-dimensional (3D) electromagnetic fields. Specifically, by varying the initial phase from 0 to 0.5π of the tightly focused generalized cylindrical vector beams (CVBs), the peak magnetic-to-electric longitudinal force ratio can be enhanced by 260% (i.e., from 0.5 to 1.8). This tunability originates from the asymmetric nature of dipole forces: the magnetic dipole force is predominantly conservative, while the electric dipole force contains a non-conservative curl component that is highly sensitive to phase-induced field vorticity. The underlying mechanism, involving continuous switching between electric-dominant and magnetic-dominant regimes, is further validated by the correlated evolution of scattering cross-sections and longitudinal field intensities. These results establish phase-modulated 3D fields as a versatile platform for tailoring magneto-electric optical forces, offering new opportunities in optical trapping, nanoparticle sorting, and nanoscale assembly.